mseal sysmap: generic vdso vvar mapping

mseal sysmap: generic vdso vvar mapping

With the introduction of the generic vdso data storage the VM_SEALED_SYSMAP
vm flag must be moved from the architecture specific
_install_special_mapping() call [1] [2] which maps the vvar mapping to
generic code.

[1] https://lkml.kernel.org/r/20250305021711.3867874-4-jeffxu@google.com
[2] https://lkml.kernel.org/r/20250305021711.3867874-5-jeffxu@google.com

Link: https://lkml.kernel.org/r/20250311123326.2686682-2-hca@linux.ibm.com
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Jeff Xu <jeffxu@chromium.org>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>